Related papers: Tau Decays and $\alpha_s$
Using the most recent release of the ALEPH $\tau$ decay data, we present a very detailed phenomenological update of the $\alpha_s(m_\tau^2)$ determination. We have exploited the sensitivity to the strong coupling in many different ways,…
Predictions for semi-leptonic decay rates of the tau lepton into two and three meson final states with one or two kaons are derived, including a discussion of K_S pi- K_S, K_L pi- K_L and K_S pi- K_L. The hadronic matrix elements are…
The evaluation, systematic analysis and numerical study of the semileptonic $\tau$-lepton decays with two mesons in the final state has been made in the frame of the standard model extended by right handed neutrinos. In the analysis,…
Recent results on measurements of the strong coupling $\alpha_S$ from LEP are reported. These include analyses of the 4-jet rate using the Durham or Cambridge algorithm, of hadronic $Z^0$ decays with hard final state photon radiation, of…
Analytic formulae are given for order alpha_s perturbative QCD corrections to the double differential distribution of the tau lepton energy and the invariant mass of the tau + antineutrino system in semileptonic decays of the bottom quark.…
The talk covers three contributions on (i) the final measurement of branching ratios and spectral functions of t decays using the full LEP-I data from ALEPH, (ii) a preliminary measurement of the t hadronic branching ratios from DELPHI and…
The measurements of the leptonic branching ratios BR(Ds->tau nu) and BR(Ds->mu nu) are reviewed. The values of the Ds decay constant fDs derived from the measurements are updated and a world average is calculated taking into account the…
The tau lepton lifetime is measured with the L3 detector at LEP using the complete data taken at centre-of-mass energies around the Z pole resulting in tau_tau = 293.2 +/- 2.0 (stat) +/- 1.5 (syst) fs. The comparison of this result with the…
The pure leptonic or semileptonic character of tau decays makes them a good laboratory to test the structure of the weak currents and the universality of their couplings to the gauge bosons. The hadronic tau decay modes constitute an ideal…
We study two and three meson decays of the tau lepton within the framework of the Resonance Chiral Theory, that is based on the following properties of QCD: its chiral symmetry in the massless case, its large-N_C limit, and the asymptotic…
Exclusive hadronic decays of the tau lepton provide an excellent framework to study the hadronization of QCD currents in a non-perturbative energy region populated by many resonances. I give a short review both on the main theoretical tools…
The four-loop determination of the strong coupling from fully inclusive observables is reviewed. Special attention is given to the low-energy measurement extracted from the hadronic $\tau$ decay width. A recent exhaustive analysis of the…
The structure of the form factors stemmed from the hadronization of QCD currents in the energy region of the resonances can be explored through the analyses of exclusive hadronic decays of the tau lepton. I give a short review on the later…
An updated measurement of alpha_s(m_tau) from ALEPH tau hadronic spectral functions is presented. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence or principle…
The QCD corrections to the R_{\tau}^{12} moment of the invariant mass distribution in hadronic decays of the tau lepton are discussed. The next-to-next-to-leading order prediction is shown to be stable with respect to change of the…
The problem of determination of $\alpha_{s}$ and the condensates from the moments of invariant mass distribution in the semileptonic tau decays is considered. It is investigated how the extracted values of alpha_s(m^{2}_{tau}) and the…
Hadronic decays of the $\tau$ lepton provide a clean environment to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results from ALEPH on…
Hadronic decays of the $\tau$ lepton provide a clean source to study hadron dynamics in an energy regime dominated by resonances, with the interesting information captured in the spectral functions. Recent results on exclusive channels are…
We present the first observation of tau lepton decays to hadronic final states with a phi-meson. This analysis is based on 401 fb^-1 of data accumulated at the Belle experiment. The branching fraction obtained is B(tau- -> phi K- nu) =…
The hadronic decays of the tau lepton can be used to determine the effective charge alpha_tau(m^2_tau') for a hypothetical tau-lepton with mass in the range 0 < m_tau' < m_tau. This definition provides a fundamental definition of the QCD…